def my_astar():
        p_queue = util.PriorityQueue()
        start = problem.getStartState()
        path = [(start, "", 0)]
        p_queue.push(path, heuristic(start, problem))
        closed_list = []
        while True:
            present_path = p_queue.pop()
            cost = present_path[-1][2]
            present_state = present_path[len(present_path) - 1][0]

            if problem.isGoalState(present_state):
                return present_path

            if present_state in closed_list: continue

            closed_list.append(present_state)
            successors = problem.getSuccessors(present_state)
            #print 'successors', successors
            #r = raw_input()

            for state in successors:
                #s = (state[0], state[1], cost + problem.getCostOfActions(
                s = (state[0], state[1], cost + state[2])
                p_queue.push(present_path +[s], cost + heuristic(state[0], problem))